Heretofore, there has been known a bar feeder for taking out a new bar by a bar take-out mechanism and feeding the bar to a bar machining apparatus. For example, the bar take-out mechanism includes a type designed to take out bars one-by-one from a bar rack by an index plate attached to a rotation shaft located above a guide rail for guiding bars to a bar machining apparatus, and then load the taken-out bar into the guide rail (see, for example, Japanese Registered Utility Model No. 3001964 (FIG. 2)).
With reference to FIG. 10, the conventional bar feeder will be described below by taking the bar feeder disclosed in Japanese Registered Utility Model No. 3001964 (FIG. 2) as an example. FIG. 10 is a fragmentary sectional view showing the bar feeder disclosed in that utility model.
As shown in FIG. 10, the bar feeder 200 comprises a guide rail 202 for guiding a bar B to a bar machining apparatus (not shown), a bar rack 204 located obliquely above the guide rail 202 and designed to allow a plurality of bars B to be placed thereon, and a bar take-out mechanism 206 for taking out the bars B one-by-one from the bar rack 204 and loading the taken-out bar B to the guide rail 202. The bar take-out mechanism 206 includes a plurality of rotatable members or disk-shaped index plates 210 which are attached, in spaced apart relation to each other, to a rotation shaft 208 located above the guide rail 202. Each of the index plates 210 has an outer peripheral surface formed with a plurality of concave portions or pockets 212 having different sizes corresponding, respectively, to various diameters of the bars B. The index plate 210 is releasably locked to the rotation shaft 208. In advance of a supply operation, the index plate 210 is locked to the rotation shaft 208 at a given position (rotational or angular position) where one 212a of the pockets 212 corresponding to a diameter of a specific type of bars B to be machined is aligned with the bar rack 204. Specifically, the index plate 210 after being released from the rotation shaft 208 is rotated to the given position where the pocket 212a corresponding to the diameter of the specific type of bars B to be machined is aligned with the bar rack 204, and then locked to the rotation shaft 208 at the given position. Although omitted in FIG. 10, the bar feeder 200 further includes a plurality of anti-vibration devices (not shown) for preventing vibrations of the bar B when this bar B is machined by the bar machining apparatus.
When the pocket 212a corresponding to a diameter of a specific type of bars B to be machined in this lot, among the pockets 212 formed in the outer peripheral surface of the index plate 210, is located at a position A1 or a position aligned with the bar rack 204, one of the bars B placed on the bar rack 204 in a line is received in the pocket 212a. Then, when the rotation shaft 208 is rotated in a direction indicated by the arrow 214 to move the pocket 212a of the index plate 210 to a position A2 or a lower position where the pocket 212a is disposed opposed to the guide rail 202, the bar B in the pocket 212a falls into the guide rail 202, i.e., the bar B is loaded into the guide rail 202. After completion of the loading of the bar B, when the rotation shaft 208 is reversely rotated in a direction indicated by the arrow 216 to move the pocket 212a of the index plate 210 back to the position A1, another one of the bars B to be loaded next is received in the pocket 212a to prepare for loading of the next bar B.
Then, the bar B loaded in the guide rail 202 is fed to the bar machining apparatus (not shown) in a direction from an upstream side to a downstream side along the guide rail 202 by use of a feed rod (not shown). Specifically, the feed rod has a front end provided with a finger chuck (not shown) for holding a rear end or upstream end of the bar B. After feeding a front end or downstream end of the bar B to a machining section of the bar machining apparatus, the feed rod moves the bar B forward by a given length of a product every time the bar machining apparatus cuts the bar B into the length of the product. When the bar B is shortened to have a length incapable of being cut into the given length of the product, the feed rod is pulled back toward the bar feeder 200, and the remaining bar is removed from the guide rail 202. The anti-vibration device is designed to have opening/closing movements interlocked with the rotation shaft 208 of the index plate 210. Specifically, when the pocket 212a of the index plate 210 is located at the position A1, the anti-vibration device is set in a closed position where it holds the bar B in the guide rail 202, so as to prevent vibrations of the bar during machining. When the pocket 212a of the index plate 210 is located at the position A2, the anti-vibration device is set to an open or release state to allow the next bar B to be loaded into the guide rail 202 without interference with the anti-vibration device.